CHAPTER XXXIII. 

 BACTERIA IN OTHER FOODS. 



ALL foods except those cooked just previous to eating contain 

 bacteria, the number and kind varying with the specific product and 

 especially the method of handling. The greater part of such 

 bacteria are without special significance. Some are beneficial and 

 play an important role in the ripening or other changes through 

 which the food passes. These are considered in a later chapter, the 

 present one being reserved for a consideration of those bacteria 

 which cause spoilage of food though not necessarily injurious to health, 

 but of importance from an economic standpoint, and the pathogenic 

 organisms which find their way into food and may infect the con- 

 sumer. 



Bacteria in Butter. Many of the bacteria which occur in unclean 

 milk multiply and give bad flavors to the butter produced from 

 such milk. This is true to such a degree that most dairies first 

 sterilize their cream and then add to it a pure culture for the ripen- 

 ing of the cream. 



Any pathogenic bacteria which find their way into the milk may 

 persist in the butter. While the typhoid organism grows well in 

 fresh milk the increased acid production tends to check their mul- 

 tiplication and may actually kill many. They are, however, fairly 

 resistant to lactic acid, as seen from the following results (Krum- 

 wiede and Noble) : 



Reaction. Number of typhoid 



Days. Per cent. bacilli. 



1.0 392,000 



7 2.2 65,000,000 



8 5.0 300,000,000 



9 113,000,000 



10 181,000 



11 . 10.0 400 



Hence, lactic acid cannot be depended upon to free butter from 

 the typhoid bacilli. Moreover, numerous investigators have found 

 typhoid bacilli in butter after varying lengths of time Bolley, 

 five to ten days; Heim, twenty-one days; Pfulel, twenty-four days; 

 Buck, twenty-seven days. Washburn obtained the organism after 

 one hundred and fifty days from butter which had been experimen- 

 tally infected with typhoid bacilli, and Boyd reports an epidemic 

 of typhoid fever which resulted from butter. Probably the longevity 

 of B. typhosus in butter would vary greatly with the temperature 

 and other factors, but it is quite evident that butter should not be 

 produced from infected milk. 



Tubercle bacilli multiply only slowly if at all in milk; hence, 

 it is the initial contamination which counts. But we have seen in 



